Sign a message

Request Sui message signatures from users through Phantom to verify address ownership without fees.

Phantom’s Sui dapp support will be deprecated on September 24, 2026. Do not start new Sui integrations with Phantom. Existing integrations can continue during the transition and should prepare for the deprecation.

When a web application is connected to Phantom, it can also request that the user signs a given message. Applications are free to write their own messages which will be displayed to users from within Phantom’s signature prompt. Message signatures do not involve network fees and are a convenient way for apps to verify ownership of an address.

try {
    const encodedMessage = new TextEncoder().encode(message);
    const signature = await provider.signMessage(encodedMessage, address);
    return signature;
} catch (error) {
    throw new Error(error instanceof Error ? error.message : 'Failed to sign message');
}